Phonons in slow motion: Dispersion relations in ultrathin Si membranes

J. Cuffe, E. Chavez, Andrey Shchepetov, P.-O. Chapuis, E.H. El Boudouti, F. Alzina, T. Kehoe, J. Gomis-Bresco, D. Dudek, Y. Pennec, B. Djafari-Rouhani, Mika Prunnila, Jouni Ahopelto, C.M. Sotomayor Torres (Corresponding Author)

    Research output: Contribution to journalArticleScientificpeer-review

    81 Citations (Scopus)


    We report the changes in dispersion relations of hypersonic acoustic phonons in free-standing silicon membranes as thin as ∼8 nm. We observe a reduction of the phase and group velocities of the fundamental flexural mode by more than 1 order of magnitude compared to bulk values. The modification of the dispersion relation in nanostructures has important consequences for noise control in nano- and microelectromechanical systems (MEMS/NEMS) as well as opto-mechanical devices.
    Original languageEnglish
    Pages (from-to)3569-3573
    Number of pages4
    JournalNano Letters
    Issue number7
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed


    • Confined phonons
    • dispersion relations
    • inelastic light scattering
    • Si membranes
    • slow phonons
    • ultrathin


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